Field of the Invention
The present invention relates to a method for producing polymer latex particle coated with silver nanoparticles. More particularly, the method is for firmly and evenly coating the silver nanoparticles onto the surface of the polymer latex particle in a specific production condition, therefore, the obtained latex particle of the present invention has well antibacterial activity, which not only is substituted to the preservative in the cosmetics, but also resolves the problem that the silver nanoparticles go into the human cells by skin, and the silver particles are dispersed in nanoscale to increase its antibacterial activity.
Description of Related Art
Recently, the cosmetics have become indispensable daily necessaries for people who love beauty. In order to elongate the effective period of the cosmetics, the chemical antibacterial agent or preservative is added into the cosmetics to extend shelf life of the cosmetics. The preservative in common use is organic chemicals such as Paraben, Phenoxyethanol, Benzoic acid, or Sorbic acid, which has good antibacterial activity. However, when long-term use of the organic chemical preservative to cause the overdose accumulation, there still has doubt that the organic chemical preservative causes the skin allergies and has toxicity.
Besides the chemical synthesized organic antibacterial agent or preservative, the well-known inorganic antibacterial agent is silver nanoparticle, which has extremely good deodorant activity and antibacterial activity and is high temperature resistant. In addition, the silver nanoparticle avoids the problem that it needs to contact ultraviolet when use a titanium dioxide photocatalyst. Accordingly, many inventions disclose that the nanoparticle is combined with different base material to make the base material having additional antibacterial activity.
For example, the TW Patent application with the Issued No. 1455778 B, “producing method for combining metal nanoparticle to the surface of base material”, comprises the following steps. A default base material is immersed into a saline solution containing metal ions with default concentration, making the metal ions attach to the base material. Then, the base material is moved out, and a reaction solution containing a default reduction solution is added onto the base material to provide energy for reducing the metal ions, which are attached on the surface of the base material, to the metal nanoparticle. Finally, the base material is dried by a default method to obtain a base material which is combined with metal nanoparticle. Accordingly, the product is not easy to remain with the harmful chemicals, so the product does not need to be processed by the complicated process. The TW Patent application with the Issued No. 1495481 B, “polysiloxane composite particle, method for making the same, and cosmetics”, discloses a polysiloxane composite particle, which can be added into the deodorant cosmetics. It is characterized that 100 mass parts of polysiloxane elastomer globule is coated with 0.5 to 25 mass parts of polysiloxane resin, wherein the polysiloxane elastomer globule has a mean diameter of 0.1 to 100 μm, and the main constituent of the polysiloxane resin is silsesquioxane and the polysiloxane resin contains inorganic micro particle with a mean diameter below 100 nm. And the TW Patent application with the Issued No. 1455718, “a composite of silver nanoparticles and clay for antibacterial growth and the making method of the same”, discloses a composite of silver nanoparticles and clay for applying to biological, medical, chemical, chemical industry, or material area (for example, antibacterial growth or medical treatment for burns and scalds). The composite is a power, comprising a metal particle and layered inorganic clay, wherein the layered inorganic clay has an aspect ratio of about 100 to 1,000 and is as the carrier of the metal particle, making the metal particle disperse in nanoscale. The composite of silver nanoparticles and clay for antibacterial growth has a size of about 5 nm to 100 nm. The layered inorganic clay can be bentonite or nanosilicate platelet. When the layered inorganic clay is bentonite, the metal nanoparticle/clay weight ratio is 1/100 to 1/13.83 or 1/6.944 to 100/1. When the layered inorganic clay is nanosilicate platelet, the metal nanoparticle/clay weight ratio is 1/13.43 to 100/1. The metal is silver.
According to the literature, although there has many application for silver nanoparticle combined with different base material, how to uniformly combine the silver nanoparticle to the base material is determined by different making method. Therefore, how to invent the best polystyrene latex particle coated with silver nanoparticles as antibacterial agent is the breakthrough direction for inventors in the related area.